Innocence is a godly gift, preserve it. If you lose your innocence, World won't look the same. (You'll get to know, how worse the world has become)It is different from the world described in Cartoons books and games or as told by teachers or friends.
You a great artist never underestimate yourself. (All the best for your art)
He surely is safe but still bad kids are not as bad as the world outside (You know what I mean)
So what type of age restricted content does it include?
If it's violence it's fine if it's something like mild violence or cartoon voilence but too much voilence is not good for a 13 yo especially senseless violence. By that I mean the kind of games where you have to kill people for no reason like for example PUBG which is I think rated for 12+ but played by kids under that age.
Gore. Try to do minimum blood and gore effects as some people don't like it and young and sentimental people get scared. Also it is not good for kids.
Don't include bad practices in your games like gambling smoking drinking and drug use.
As for other exclusive 'adult' stuff don't even think of using it because it's also very bad of adults to include it in their game. I think you get what I'm trying to say.
Hope you found this advice useful.
